Inverter or generator?

This is a discussion on Inverter or generator? within Gadgets, Computers & Software, part of the Shifting gears category; Originally Posted by DerAlte
So you mean to say having a chimney on a car (forget aesthetics for a moment) ...

So you mean to say having a chimney on a car (forget aesthetics for a moment) is going to improve the efficiency of a car engine? Or that the same diesel engine mounted on a truck prime mover (has a chimney) will be more efficient than in a bus? Wonder why no one thought about it till now.

I'll tell you what I mean to say:

chimney creates something called "negative pressure" due to hot lighter than air gases rising through it - the taller the chimney the more negative pressure it creates

The effect is so strong that in mines it was used (in liu of fans - till electricity became common) to create a draft so people could breath

In case of the diesel engine the negative pressure thus generated will reduce the back-pressure on the exhaust side - no matter what you think

Reduced back pressure should reduce pumping losses - I'm not sure about this part though. I mean the losses due to back pressure for the engines used in gensets may not be high enough to make a significant difference.

Quote:

Originally Posted by Thad E Ginathom

This little Kohler KK06 doesn't even have a pipe on the outside, unlike the larger models we see outside offices, often having silencer and pipe/chimney externally.

Do you have a link or something to the spec sheets? I'm interested in kVA and price - might buy one of my own if it is affordable

Stuff like autostart, with Kohler (rep visit booked) starts with the 15kvs (3-phase) model. Obviously a lot more (2.7 I think) than the number I first thought of.

Also, I have a worry. Have I heard somewhere that gensets don't take kindly to running on a low load for extended periods? I know from my boating days not to idle a cold diesel for long

Hi, I did not read your complete requirements but I myself recently bought 82.5 kVA genset. That is for a true load of about 80% ie., 60 kVA. Kirloskar with Stamford alternator and AMF panel. This combination has thus far been vouched for industrial units that have been running them for past 18 years. Infact, i cancelled on Mahindra though cheap I saw 5 years old canopy all rusted.

The smaller genset do not have a digital governor and thus the genset will run at optimal load only. Thus you do not have to worry about low load, rather high cost per unit consumed.

I had expected to find that Mahindra would come in winning in terms of features for the price but...

Quote:

i cancelled on Mahindra though cheap I saw 5 years old canopy all rusted.

That is enough to take it off my list. We have a lot of pollution here: the atmosphere is very corrosive.

I see a lot of Kirloskar units outside buildings. Looks like they are popular. In terms of finish, the Kohler looked really good in the exhibition, but then, so do cars in a showroom: it is a few years down the line that we find out.

I had expected to find that Mahindra would come in winning in terms of features for the price but...
That is enough to take it off my list. We have a lot of pollution here: the atmosphere is very corrosive.

I see a lot of Kirloskar units outside buildings. Looks like they are popular. In terms of finish, the Kohler looked really good in the exhibition, but then, so do cars in a showroom: it is a few years down the line that we find out.

We have players like Sudhir/Jakson etc. who are nothing more than assemblers of the Cummins engine and Stamford alternator governors with the class defined all weather canopy. Excuse my previous post I got a Cummins engine. Kirloskar also uses the same thus I invariably used their name.

I got mine from Sudhir. I got a good deal before the financial year closure and they delivered it as desired.

About pricing : You need to look at the components rather than the complete thing as whole. e.g. ABB L&T switch gear will be anyway more expensive than local switch. The sheet metal should have proper powder coating and rain guard rather than shiny color. The contacts should be properly fused to the bus contractor rather than just plain old tangled wires. To give you an example an AMF panel was quoted to me for 1lacs and another one I bought was 60k the difference was that the components were different. Thus do not go by price alone. Cheers!

I'm shopping for a true sine-wave inverter for my house. Our house is old and does not have any special provision/wiring for an inverter. (Of course the house is new enough that we have a separate wiring for heating and lighting.) I contacted a few dealers today. Some of them visited my house and left me totally confused. Here is my dilemma:

A. Let's say I have 8 lights, 3 fans, a CRT TV and a computer being used simultaneously with raw power supply.

B. Let's say I want to use only 5 lights, 2 fans and a TV when there is a power cut for about 2 hours.

So far I believed I had to plan only for B and that A didn't really matter because I could choose to switch off stuff and reset the UPS in case of a power cut. However one gentlemen who visited says that A is equally important because even when the power supply is available, the load is actually being connected to the inverter and therefore I need to plan with A in mind or else the inverter fuse will blow off frequently.

Is this how it actually works? As per his calculation I might actually require a 2kVA inverter which will be a mighty expensive affair.

I'm shopping for a true sine-wave inverter for my house. Our house is old and does not have any special provision/wiring for an inverter. (Of course the house is new enough that we have a separate wiring for heating and lighting.) I contacted a few dealers today. Some of them visited my house and left me totally confused. Here is my dilemma:

A. Let's say I have 8 lights, 3 fans, a CRT TV and a computer being used simultaneously with raw power supply.

B. Let's say I want to use only 5 lights, 2 fans and a TV when there is a power cut for about 2 hours.

So far I believed I had to plan only for B and that A didn't really matter because I could choose to switch off stuff and reset the UPS in case of a power cut. However one gentlemen who visited says that A is equally important because even when the power supply is available, the load is actually being connected to the inverter and therefore I need to plan with A in mind or else the inverter fuse will blow off frequently.

Is this how it actually works? As per his calculation I might actually require a 2kVA inverter which will be a mighty expensive affair.

It depends on what mode the Inverter uses.

A. Line Interactive. This is the most economic model. The Inverter is bypassed when there is mains power, and is connected only when power goes. In this case "B" is the scenario applicable.

B. Online. Here the inverter is always on and the inverter supplies to all load connected. In this case the scenario "A" is applicable.

Note that the above modes are independent of whether the inverter is "Sine Wave" or not.

In old houses, each circuit is separate with its own fuse/MCB. If you identify which circuits will be using Inverter power, an electrician can isolate the circuits and wire them up for an inverter use.

I'm shopping for a true sine-wave inverter for my house. Our house is old and does not have any special provision/wiring for an inverter. (Of course the house is new enough that we have a separate wiring for heating and lighting.) I contacted a few dealers today. Some of them visited my house and left me totally confused. Here is my dilemma:

A. Let's say I have 8 lights, 3 fans, a CRT TV and a computer being used simultaneously with raw power supply.

B. Let's say I want to use only 5 lights, 2 fans and a TV when there is a power cut for about 2 hours.

So far I believed I had to plan only for B and that A didn't really matter because I could choose to switch off stuff and reset the UPS in case of a power cut. However one gentlemen who visited says that A is equally important because even when the power supply is available, the load is actually being connected to the inverter and therefore I need to plan with A in mind or else the inverter fuse will blow off frequently.

Is this how it actually works? As per his calculation I might actually require a 2kVA inverter which will be a mighty expensive affair.

800 VA inverter should be ok for you if you are careful. I have a Sukam 800 VA inverter/UPS, which works well for me(have similar requirements as yours), except on days when there are frequent/long power failures, which are once in a blue moon.
Based on experience, would advise anyone using a PC at home to go in for a two-battery inverter, which is a little higher capacity (1.2 kva or higher), for peace of mind.
Anyone needing to use AC, is probably better served by a diesel generator.

A. Line Interactive. This is the most economic model. The Inverter is bypassed when there is mains power, and is connected only when power goes. In this case "B" is the scenario applicable.

B. Online. Here the inverter is always on and the inverter supplies to all load connected. In this case the scenario "A" is applicable.

Note that the above modes are independent of whether the inverter is "Sine Wave" or not.

In old houses, each circuit is separate with its own fuse/MCB. If you identify which circuits will be using Inverter power, an electrician can isolate the circuits and wire them up for an inverter use.

Which of the two modes do the well known brands use?

Well, it seems like he was obviously trying to sell an inverter that uses Online mode. He deals with all the branded inverters, but he is particularly interested in selling me a local one which he claims is very good (but is also expensive). He also says it uses an IGBT. What are its pros and cons? Do any of the branded ones use an IGBT?

Most of the less expensive models are "Line Interactive", as this mode stresses the "Inverter" portion less, and can use less expensive components. These Inverters also give "Squarish" waveform, with lots of harmonics, which may affect some appliances. An easy fix is to have a filter in the circuit.

Most of the "Online" versions are Pure Sine Wave inverters, and cost at least twice as much. Online Inverters are used primarily in Data Centres due to
. 100% power availability, no switch over time
. Better regulation and filtering
. Isolated from the mains, hence power fluctuations are not propagated to the load.

In general "Line Interactive" are sufficient for home use, provided they have High/Low Volage cut-off. Modern Electronics uses switching regulators, hence are less affected by mains fluctuations. In some cases the electronics in Electrical Appliances are not that well designed and may succumb to mains voltage fluctuations and harmonics from an Inverter (WM, MW, Refrigerators).

Well, it seems like he was obviously trying to sell an inverter that uses Online mode. ... He also says it uses an IGBT. What are its pros and cons? Do any of the branded ones use an IGBT?

Usually an inverter destined for normal home uses will be of line interactive type to save costs. You will need hugh transformers to supply the full load as well to keep the batteries charged in the case of Online inverters. Online UPS designed for computers tend to be big and expensive than line interactive types.

IGBT (Insulated Gate Bipolar Transistor) are power transistors capable of higher operating currents for the same die (silicon slice it is made of) meaning you can use just a pair to operate your inverter as against several MOSFET (metal oxide semiconductor field ) operating in parallel. This gives the advantage that the cooling fan and the heat sinks can be smaller and hence can be more efficient.

Sorry Aroy. By the time I finished typing I saw that you have covered the main points.